Hoag's Object Is a Galaxy Within a Galaxy Within a Galaxy (and Nobody Knows Why)

Hoag's Object Is a Galaxy Within a Galaxy Within a Galaxy (and Nobody Knows Why)

Look closely at the serpent constellationslithering through the northern sky, and you might see a galaxy within a galaxy within a galaxy.
This cosmic turducken is known as Hoag's object, and it has befuddled stargazers since astronomer Arthur Hoag discovered it in 1950. 

The object in question is a rare, ring-shaped galaxy measuring some 100,000 light-years across (slightly larger than the Milky Way) and located 600 million light-years from Earth. In a recent image of the oddball object taken by the Hubble Space Telescope and processed by geophysicist Benoit Blanco, a bright ring of billions of blue stars forms a perfect circle around a much smaller and denser sphere of reddish stars. In the dark gap between the two stellar circles, another ring galaxy — much, much farther away from us — peeks out to say hello.
What's going on here, and what tore Hoag's object in two? Astronomers still aren't sure; ring galaxies account for less than 0.1% of all known galaxies, and so they aren't the easiest objects to study. Hoag himself suggested that the galaxy's peculiar ring formation was merely an optical illusion caused by gravitational lensing (an effect that occurs when extremely high-mass objects bend and magnify light). Later studies with better telescopes disproved this idea.
 
PLAY SOUND
Another popular hypothesis suggests that Hoag's object was once a more common, disk-shaped galaxy but an ancient collision with a neighboring galaxy ripped a hole through the disk's belly and permanently warped its gravitational pull. If such a collision occurred in the last 3 billion years, then astronomers looking through radio telescopes should have been able to see some of the fallout from the accident. No such evidence has been found. 
If there was a cosmic crash at the core of Hoag's object, it must have happened so long ago that all the evidence has been swept away. With only a handful of other known ring galaxies available to study (none of which shows the perfectly symmetrical characteristics found in this one), Hoag's object remains a mystery wrapped in a riddle inside an enigma 

Comments

Post a Comment

Popular posts from this blog

You may soon be able to ride to the edge of space from Alaska in a Balloon

Image
You may soon be able to ride to the edge of space from Alaska in a Balloon Florida-based startup firm Space Perspective plans to use the Pacific Spaceport Complex in Kodiak to serve as one of the launch sites for the vehicle, called the Spaceship Neptune A company wants to use an advanced balloon to fly customers from Earth’s surface in Alaska to the highest reaches of the planet’s atmosphere. Florida-based startup firm Space Perspective plans to use the Pacific Spaceport Complex in Kodiak to serve as one of the launch sites for the vehicle, called the Spaceship Neptune,  The Anchorage Daily News  reported on Sunday. The balloon rides will be manned by a flight crew taking eight passengers in a pressurized capsule suspended beneath a hydrogen balloon the size of a football stadium. Each passenger could pay an estimated $125,000 for a six-hour journey. Mark Lester, CEO of Alaska Aerospace Corp., said the high-altitude rides will be available from Kodiak in a few years and will ...
Read more

Committee recommends review of planetary protection policies

Image
Committee recommends review of planetary protection policies WASHINGTON — The NASA Advisory Council has recommended that NASA review its existing planetary protection guidelines to balance the needs of science and exploration, an effort that could set the stage for a similar revision at the international level. The council, during a two-day meeting at NASA Headquarters Dec. 10–11, adopted a recommendation calling on NASA to establish an interdisciplinary committee of experts to review the agency’s current requirements for preventing contamination of other worlds by NASA spacecraft as well as any contamination of the Earth by materials brought back from those worlds. “NASA should establish a multidisciplinary task force of experts from industry, the scientific community, and relevant government agencies, to develop U.S. policies that properly balance the legitimate need to protect against the harmful contamination of the Earth or other celestial bodies with the scientific, social, and e...
Read more

Surprise! There's more water on Jupiter than anyone thought

Surprise! There's more water on Jupiter than anyone thought Jupiter  appears to have more water than anyone expected. Newly released data from  NASA's Juno probe shows that water may make up about 0.25% of the molecules in the atmosphere over Jupiter's equator. While that doesn't sound like much, the calculation is based on a prevalence of water's components, hydrogen and oxygen, three times more than at the sun. The new measurements Juno obtained are much higher than a previous mission suggested. The surprise result has scientists delving deep again into results from  NASA's Galileo mission to Jupiter , which obtained drier results in 1995 when engineers deliberately threw the spacecraft into Jupiter's atmosphere. (Galileo was low on fuel and NASA didn't want to take the chance, even if it was a slight one, of the spacecraft accidentally crashing on a potentially habitable icy moon.) Reconciling the results from Galileo and Juno is key for sc...
Read more